-LRB- CNN -RRB- -- Hey Mars ! We 're back ! Hope you do n't mind if we cruise around in our scientific SUV to grab some historic data and snap some breathtaking images . Oh , and we might do some Martian doughnuts in your front yard .

Now that the Mars rover Curiosity is safely parked , NASA 's unmanned planet crawler appears ready to roll . A car salesman would have a ball selling this beauty . It 's loaded with an array of sophisticated cameras , a `` rocker bogie '' suspension , a robotic arm , 2 gigs of flash memory , a rock-vaporizing laser -LRB- !!!! -RRB- and a plutonium-fueled power system . It operates by remote control from millions of miles away and has a blazing top speed of 1.5 inches per second .

Sticker price -LRB- including delivery -RRB- : $ 2.6 billion .

During its expected lifespan of 23 months , all this cool hardware could help solve big mysteries : Has life ever existed on Mars ? What can Mars tell us about our own planet ? Can we benefit from Martian resources ?

But there are less romantic questions swirling around the fourth rock from the sun : Is the price tag really worth it ? Who will pay for the first manned mission to Mars ? Could manned space missions be replaced by robotic exploration ?

The answers may be hard to see amid all the rover revelry . And this is n't the first time rovers have churned up this kind of excitement .

In 1997 , a smaller NASA robot on Mars -- Sojourner -- lit up the Web .

`` Back when the Internet was young , it was the largest Internet event in the history of that medium , '' Curiosity team member James Bell told CNN on Monday . The little rover found clues suggesting that Mars once had a thicker atmosphere and liquid water . Sojourner and its parent spacecraft Pathfinder cost $ 265 million -LRB- PDF -RRB- .

`` Later , in 2004 , when the Spirit and Opportunity rovers landed , it became one of the largest worldwide Internet sensations , '' said Bell , who also worked on that mission . `` It slammed NASA 's website . '' The rovers scored several discoveries including evidence of an ancient wet environment on Mars . Price tag for Spirit and Opportunity : $ 800 million -LRB- PDF -RRB- .

Nowadays -- at least for some space travel fans -- Martian robots are n't so cool anymore . Curiosity `` is just another box with wheels on Mars , '' says CNN commenter It_could_always_be_worse . `` Develop useful technology -- not this shooting of boxes with wheels all over the place . SEND PEOPLE , and I will be proud . ''

CNN commenter Max Lewes disagrees . `` This really was a HUGE leap from previous missions . ''

Related story : Curiosity 's wild ride

After the initial excitement of Monday 's landing , even the Curiosity team jokingly acknowledged the first dusty black and white photos from the rover have already lost their luster .

`` It 's not such a great picture anymore , '' a smiling Mike Watkins told reporters . He promised color and panorama photos in the coming days .

Seriously , no matter how successful unmanned missions might be , robots will never replace the need for human space exploration , says Bell .

In a sense , Curiosity is performing a scouting mission for a manned U.S. mission to Mars that President Barack Obama predicts will happen in his lifetime .

NASA administrator Charles Bolden gets even more specific : Manned missions to Mars are at least 18 years away -- sometime in the 2030s .

But first , mission planners need more information about the Martian surface so they can choose the best landing sites .

`` We do n't want astronauts to be surprised , '' says Bell . Robot missions , such as Surveyor , preceded the Apollo moon landings , and these Martian probes are performing similar tasks .

Putting a monetary value on space exploration is impossible , experts say , because there are too many unanswered questions , such as whether Mars , the moon or asteroids hold precious minerals , water and cheap energy resources that could be mined and brought back to Earth .

`` The reason to send humans will be because we have to , '' Bell says . `` If some things can be done by robots , they should be done by robots . But sending a drill rig to Mars or Jupiter 's moon Europa to tap into an aquifer that may have living organisms in it -- those kinds of things will require people . ''

Then there 's the unknown value of newly discovered knowledge . Scientists want to know what Mars can tell us about our own planet 's climate and geology . That knowledge , experts say , could help solve difficult environmental problems on Earth .

`` It 's human nature to explore , '' says Bell . `` By going to difficult or dangerous places , we carry the rest of our species along with us . These stories become part of part of our culture , part of our heritage , part of our shared need to explore the worlds around us . it 's a human endeavor that is part science , part inspiration . ''

Related story : Earth loves Mars -- why we 're crushing on the red planet

By the way , Curiosity has fostered jobs , says NASA ; more than 7,000 people have worked on the project across 31 states .

What 's next ? NASA plans test flights for Orion -- a spacecraft designed to carry astronauts outside low Earth orbit -- as soon as 2014 . In 2017 , NASA plans to launch Orion with a new heavy-lift rocket NASA calls the Space Launch System .

But big questions remain : How would NASA pay for development of a landing vehicle ? Or a vehicle for astronauts to travel on the Martian or lunar surface ? Or how would it develop an astronaut habitat suitable for the months it would take to travel to Mars or to asteroids ?

NASA 's proposed budget for 2013 is $ 17.7 billion -- $ 59 million less than 2012 -LRB- PDF -RRB- . It includes a `` lower cost program '' for unmanned missions to Mars -LRB- PDF -RRB- . For perspective , the Mars rover 's $ 2.6 billion price tag equals about 14.7 % of NASA 's proposed 2013 budget .

However , the budget also calls for more money for manned deep space programs , including almost $ 3 billion for Orion and the Space Launch System .

In May , something happened right above our heads that gave us a glimpse into the future of Mars exploration . That 's when the private firm SpaceX successfully docked its Dragon spacecraft with the orbiting international space station .

NASA is studying a proposal -- referred to as Red Dragon -- that would use a SpaceX rocket for less-expensive unmanned missions to Mars .

But robot missions are just stepping stones to what many experts say is a foregone conclusion .

`` Humans are going to live on Mars in the president 's expected lifetime , '' says commercial space consultant Charles Miller , a former NASA executive . `` It will happen as a partnership between U.S. entrepreneurs and private industry and NASA . ''

Complete coverage of Mars

So what do you think ? Are billion-dollar , planet-crawling robots worth the money ? Do you think astronauts will set foot on Mars within your lifetime ? Share your opinion in the comments section below .

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Mars robot Curiosity `` just another box with wheels , '' says commenter

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Expert : Manned Mars missions and Martian robots both important

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NASA will partner with private industry for manned missions , says consultant

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Obama , NASA predict manned Mars landing as soon as 18 years